| Translokin is an intracellular mediator of FGF 2 trafficking . ^^^ Here we show that Translokin , a cytoplasmic protein of relative molecular mass 55 , 000 ( M ( r ) 55K ) , interacts specifically with the 18K form of FGF 2 . ^^^ As Translokin does not interact with FGF 1 , we used a strategy based on FGF 1 FGF 2 chimaeras to map the interacting regions in FGF 2 and to generate Nb1a2 , a non interacting variant of FGF 2 . ^^^ Inhibiting Translokin expression by RNA interference reduces the translocation of FGF 2 without affecting the intracellular trafficking of FGF 1 . ^^^ Our data show that the nuclear association of internalized FGF 2 is essential for its mitogenic activity and that Translokin is important in this translocation pathway . . ^^^ |